1st of all, don't get an 8600. you can score way better deals than that. go to www.pctorque.com
and check out the 3790. it's got the same cpu as the 8600, but better vcard (9700 vs 9600). really good retailor, too.
if you dn't want a wuxga (1920x1200), you can get a wsxga (1680x1020) or wxga (1440x900). it's all personal preference. on lcd's if you change the res. from the native to a different res, the image will become blurry, so best to stay on native res at all times.
light leakage is basically light "leaking" from the bottom of the screen. i can't think of a better description. search notebookforums.com for some pics of it. you don't want to have it.
go to bestbuy and try typing something on one of their laptops. most laptops' keyboards feel about the same (though i've heard that ibm has the best keyboards). once you get used to it, you'll be fine with it. i know people that prefer it to a desktop keyboard!
basically, there are 4 cpu's you can get. p4, amd, and pentium m. centrino is a combo of a pentium m cpu, intel mobo, and intel wifi card. p4 givesgood app performance (same as on a desktop), but very short battery life. not more than 1:15. amd is good for gaming, same as the desktop version of it. battery life is around 2 hours. pentium m has the longest battery life, around 4-5 hours. it also, surprisingly, has very good performance. it's about as good as the amd in games (thanks to 2mb cache), and in office apps is as good as or better than the p4. p4 is best in apps like video/photo editing, programming, things like that.
hope i've helped. aandtech.com has some really good benchmarks of all 3 cpu's. one more thing. you should settle for nothing less than a 9700 vcard. everything below that is pure junk imo.